/**
 * hoverIntent is similar to jQuery's built-in "hover" function except that
 * instead of firing the onMouseOver event immediately, hoverIntent checks
 * to see if the user's mouse has slowed down (beneath the sensitivity
 * threshold) before firing the onMouseOver event.
 *
 * hoverIntent r6 // 2011.02.26 // jQuery 1.5.1+
 * <http://cherne.net/brian/resources/jquery.hoverIntent.html>
 *
 * hoverIntent is currently available for use in all personal or commercial
 * projects under both MIT and GPL licenses. This means that you can choose
 * the license that best suits your project, and use it accordingly.
 *
 * // basic usage (just like .hover) receives onMouseOver and onMouseOut functions
 * $("ul li").hoverIntent( showNav , hideNav );
 *
 * // advanced usage receives configuration object only
 * $("ul li").hoverIntent({
 *	sensitivity: 7, // number = sensitivity threshold (must be 1 or higher)
 *	interval: 100,   // number = milliseconds of polling interval
 *	over: showNav,  // function = onMouseOver callback (required)
 *	timeout: 0,   // number = milliseconds delay before onMouseOut function call
 *	out: hideNav    // function = onMouseOut callback (required)
 * });
 *
 * @param  f  onMouseOver function || An object with configuration options
 * @param  g  onMouseOut function  || Nothing (use configuration options object)
 * @author    Brian Cherne brian(at)cherne(dot)net
 */
(function ($) {
  $.fn.hoverIntent = function (f, g) {
    // default configuration options
    var cfg = {
      sensitivity: 7,
      interval: 100,
      timeout: 0,
    };
    // override configuration options with user supplied object
    cfg = $.extend(cfg, g ? { over: f, out: g } : f);

    // instantiate variables
    // cX, cY = current X and Y position of mouse, updated by mousemove event
    // pX, pY = previous X and Y position of mouse, set by mouseover and polling interval
    var cX, cY, pX, pY;

    // A private function for getting mouse position
    var track = function (ev) {
      cX = ev.pageX;
      cY = ev.pageY;
    };

    // A private function for comparing current and previous mouse position
    var compare = function (ev, ob) {
      ob.hoverIntent_t = clearTimeout(ob.hoverIntent_t);
      // compare mouse positions to see if they've crossed the threshold
      if (Math.abs(pX - cX) + Math.abs(pY - cY) < cfg.sensitivity) {
        $(ob).off('mousemove', track);
        // set hoverIntent state to true (so mouseOut can be called)
        ob.hoverIntent_s = 1;
        return cfg.over.apply(ob, [ev]);
      } else {
        // set previous coordinates for next time
        pX = cX;
        pY = cY;
        // use self-calling timeout, guarantees intervals are spaced out properly (avoids JavaScript timer bugs)
        ob.hoverIntent_t = setTimeout(function () {
          compare(ev, ob);
        }, cfg.interval);
      }
    };

    // A private function for delaying the mouseOut function
    var delay = function (ev, ob) {
      ob.hoverIntent_t = clearTimeout(ob.hoverIntent_t);
      ob.hoverIntent_s = 0;
      return cfg.out.apply(ob, [ev]);
    };

    // A private function for handling mouse 'hovering'
    var handleHover = function (e) {
      // copy objects to be passed into t (required for event object to be passed in IE)
      var ev = jQuery.extend({}, e);
      var ob = this;

      // cancel hoverIntent timer if it exists
      if (ob.hoverIntent_t) {
        ob.hoverIntent_t = clearTimeout(ob.hoverIntent_t);
      }

      // if e.type == "mouseenter"
      if (e.type == 'mouseenter') {
        // set "previous" X and Y position based on initial entry point
        pX = ev.pageX;
        pY = ev.pageY;
        // update "current" X and Y position based on mousemove
        $(ob).on('mousemove', track);
        // start polling interval (self-calling timeout) to compare mouse coordinates over time
        if (ob.hoverIntent_s != 1) {
          ob.hoverIntent_t = setTimeout(function () {
            compare(ev, ob);
          }, cfg.interval);
        }

        // else e.type == "mouseleave"
      } else {
        // unbind expensive mousemove event
        $(ob).off('mousemove', track);
        // if hoverIntent state is true, then call the mouseOut function after the specified delay
        if (ob.hoverIntent_s == 1) {
          ob.hoverIntent_t = setTimeout(function () {
            delay(ev, ob);
          }, cfg.timeout);
        }
      }
    };

    // bind the function to the two event listeners
    return this.on('mouseenter', handleHover).on('mouseleave', handleHover);
  };
})(jQuery);
